Bruce Farling - July 13, 2009
Montana Trout Unlimited
Invasive Species
Montana Public Radio Commentary –July 13, 2009
Bruce Farling, Montana Trout Unlimited
In a recent issue of New Yorker, science scribe Elizabeth Kolbert outlines the basic hypothesis of mass extinctions – events in which large portions of the earth’s biological community disappear over a compressed time period, at a pace that can’t generally be attributed to the slower process of natural selection. Many scientists believe some 20 mass extinctions have occurred in the past half a billion years, with five of them being especially dramatic. The causes are speculative, but there is large-scale agreement that the fifth of the big mass extinctions, which occurred 65 million years ago in the Cretaceous Period when 75 percent of all species on Earth, including the dinosaurs, disappeared in a geological wink of the eye, resulted from a massive asteroid colliding with the planet.
Today, many scientists maintain that a sixth big extinction is occurring, and the asteroid is humankind.
Some experts project that at current trends, half of the species we know today could be gone by the end of the century. Beside the profound effect human-induced climate change is having on the survivability of many species, there is another significant mechanism leading to the demise of many plants and animals. And that’s the human-caused transport, deliberate and otherwise, of species around the globe. Quick and convenient travel between hemispheres and among continents – as well as incompletely informed but deliberate introductions of non-native species into new habitats – are having acute effects on indigenous species. Many native species can’t compete with or adapt to the invaders. And that is why, for instance, frog populations are swiftly disappearing worldwide. Scientists have pegged fungi transported by people as a primary culprit in the rapid disappearance of many frog species. The New Yorker article also detailed the dramatic harm foreign fungi, transported inadvertently by humans, is having on different bat species – both common and rare -- in the Northeast United States.
Unfortunately, Montana’s plant, wildlife and fish communities are not immune to the effects of new invasive species. Cheatgrass is transforming native short-grass prairie, displacing critical habitat for dwindling prairie sparrows and longspurs. Old World invaders such as spotted knapweed and leafy spurge are overrunning native bunchgrass communities, replacing them with simplified, erosion prone landscapes that over time can’t even support Montana’s once-abundant state flower, the Bitterroot. Russian olives, planted by well-meaning farmers and extension agents, are marching up the Yellowstone River, replacing cottonwood galleries that for millennia have provided food and cover for species dependent on rich and diverse riparian corridors, including most of Montana’s nesting birds.
For years, understandably, anglers have lauded the introduction of rainbow trout, native to California, and brown trout, which originated in Europe, to our streams and rivers. And though these fish, like the similarly non-native eastern brook trout, have produced wonderful angling, they have also displaced native grayling, cutthroats and bull trout, all which now occur in just fractions of their original ranges.
For good reason, much has been made of whirling disease, the destructive product of a two-part parasite native to Europe and first documented in Montana in 1994 when it was blamed for reducing the famous Madison River wild trout population by 90 percent. But potential new aquatic invaders loom, such as quagga and zebra mussels. Yet to be detected here, but edging west from the Midwest, they could devastate aquatic communities in revered waters such as the Missouri River or Flathead Lake.
Protecting native biological diversity in Montana by preventing or corralling invasions of new, unwanted species in Montana is a colossal task. It already costs the state millions of dollars.
Some people say we should let nature take its course, that it is a fool’s errand to prevent or suppress harmful invasive species -- as if introducing plant or animal species that would never occur here is natural. But besides the obvious economic costs the demise of biological heritage means – the loss of species that are beneficial to our economy or technological development -- there is another loss that is incalculable and sad to contemplate. For ultimately no price can be placed on the bloom of a rare forest orchid or the chirring of chorus frogs on a still Montana evening.
This is Bruce Farling of Montana Trout Unlimited. Contact us at www.montantu.org
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